The work called for in this contract will involve the preparation of radieistopically labeled proteoglycans from chick limb bud chondrocyte cultures. The proteoglycans will be labeled according to different pulse and pulse for further in-house experimentation. The chick limb bud cultures will be chondrocyte cultures can be obtained which represent different times in development. The methods used for the preparation of the cultured chondrocytes of the proteoglycans obtained from them are established and have been described in the literature.